Interceptor transformer



Feb. 3, 1959 J. R. WIEGAND INTERCEPTOR TRANSFORMER Filed March 7, 195698kt woke wzkc [04kt Ti CENTER FREQUENCY INVENTOR.

f (K'LOMLEE) JOHN R. WIEGAND United rates Patent G INTERCEPTGRTRANSFORMER John R. Wiegand, North Valley Stream, N. Y.

Application March 7, 1956, Serial No. 570,160 '4 (Ilaims. or. 336-221)This invention relates to interceptor transformers useful as anelectrical oscillation control device in a suitable electrical circuit.

It is a principal object of the present invention to provide an improvedinterceptor transformer which may be used in a high gain radio frequencyor high frequency amplifier, particularly one employing a transistor asan active element.

Another object is to provide a miniature interceptor transformer whichmay be used as a component of an oscillator, interstage coupler,discriminator, amplifier or impedance matching device.

A further object is to provide an electrical oscillation control deviceuseful in a low voltage transistor circuit including inductance andcapacitance elements.

A further object is to provide a miniature interceptor transformerincluding primary and secondary coils in crossed positions andinterwoven with each other, with magnetic cores or windings crossed andinterwoven at the junctions of the crossed coils.

The general purpose and mode of operation of inter-' ceptor transformersis disclosed in my prior Patent 2,479,656, as well as in my co-pendingapplications 332,357 filed January 21, 1953, now Patent No. 2,740,096and 449,838 filed August 16, 1954, now Patent No. 2,798,987. In thepresent device primary and secondary coils are crossed and interwoven sothat their geometric and magnetic axes intersect at right angles toproduce balanced magnetic fields. At the intersections of the coilswhich occur at opposite ends of a common diametral region are pairs ofcrossed, mterwoven and magnetically balanced cores of magnetic wire. Bycrossing and interweaving the coils of the transformer the short timecharge and discharge effects are improved without increase of reversefeedback efiects to a source of oscillation. For best operation one coilshould be connected in series with a capacitance while the interwovencrossed coil should have a capacitance connected across its terminals.

The two interwoven coils may be interconnected so that their inductancemay be matched with suitable transistors to produce electricaloscillations ranging from one cycle to several megacycles per second. Adirect current source such as a battery may be used as the source ofelectrical energy.

The present device may be more economically manufactured than previouslyknown types of interceptor transformers, and requires a minimum ofadditional circuit components when used in a transistor circuit toproduce self-excited oscillations.

An interceptor transformer according to the invention may have theoverall dimensions of a quarter to a third of an inch, hardly largerthan a sphere of one-third of an inch diameter. When used with atransistor of comparable dimensions, the invention makes possible theconstruction at reasonable cost of smaller miniature radio receivers andtransmitters than have heretofore been manufactured.

rat-tented Feb. 3, M9553 For further comprehension of the invention, andof the objects and advantages thereof, reference will be had to thefollowing description and accompanying drawings, and to the appendedclaims in which the various novel features of the invention are moreparticularly set forth.

In the accompanying drawings forming a materal part of this disclosure:

Fig. 1 is a perspective view of an interceptor transformer embodying theinvention.

Fig. 2 is a plan view of crossed coils according to the invention.

Fig. 3 is a plan view of the interceptor transformer of Fig. l withportions of coil and core turns exposed.

Fig. 4 is a perspective view of a packaged interceptor transformer.

Fig. 5 is a schematic diagram of an amplifier circuit embodying theinvention.

Fig. 6 is a schematic diagram of an oscillator circuit.

Fig. 7 is a schematic diagram of a discriminator circuit.

Fig. 8 shows a characteristic curve of the discriminator circuit.

The device shown in Fig. 1 includes a toroidal primary winding 10 whichis a substantially flat circular coil of copper wire having terminals11. A toroidal secondary winding 12. which is another substantially fiatcircular coil of copper wire is interwoven and linked with the primarywinding at an angle of ninety degrees. Winding 12 has terminals 13. Thewire in both coils is fine enameled or insulated Wire.

Figs. 2 and 3 show the interwoven arrangement of the coils 10 and 12.The coils are interwoven turn by turn and the intersections at oppositesides of the coils occur at points in a common diametral region. Thecoils have substantially the same physical dimensions and are soarranged that their respective geometric and magnetic axes coincide andintersect at an angle of ninety degrees at a central point within thecoils.

A pair of generally toroidal cores 14, 15 and another pair of generallytoroidal cores 16, 17 are each interwoven and linked together andencircle the intersections of the coils. Each core is a smallsubstantially flat circular winding of magnetic wire such as soft ironor the like. Core 14 is disposed at an angle of ninety degrees to core15, and core 16 is disposed ninety degrees to core 17. Each core of aninterwoven pair intersects the other at opposite ends of a commondiametral region. All intersections or junctions of coils it 12 andcores i4, 15 and 16, 17 thus lie on points in the common diametral axisof region A-A. The cores are disposed at angles of forty-five degrees tothe coils are shown in -Fig. 3. Thus the magnetic and geometric axis ofeach core is disposed at an angle of forty-five degrees to the magneticaxis of each coil.

This crossing and interweaving of the coils with each other and thecores with each other, and the encircling of the coils by the coresinsures magnetic balancing of the coiis with each other, magneticbalancing of the cores with each other, and magnetic balancing of thecores and coils with each other.

The coils may be covered with an external protective wrapping 2i) andthe cores may have similar wrappings if desired.

Fig. 4 shows a miniature cubical structure 21 containing an interceptortransformer or interceptor oscillationformer as it is sometimesdesignated. This structure may be a plastic member in which the deviceis potted. One such structure which has been constructed has a maximumthickness of less than one-half inch and is usable in an oscillatorcircuit as shown in Fig. 6. The present device has a more compactstructure than has heretofore been known in devices of this type. Thecoils it} and 12 may have maximum diameters of the order of one-quarterU inch or less and the cores E L-17 may be considerably smaller. 7

In the circuit of Fig. is shown a high gain amplifier circuit employinga transistor 22. input terminal 23 is connected to the input electrode25 via capacitor C input terminal 24 is grounded Output terminal 26 isconnected to the collector electrode 27. Output terminal 28 is grounded.An output load'resistor R1 is connected across the output terminals.Resistor R is connected be tween resistor R and the junction ofcapacitor C and the plate of the transistor. with secondary coil 1 isconnected between capacitors C and C One of terminals ill and one ofterminals 13 are directly connected together or may be joined by jumperwire 29. Battery 31 provides energy tothe circuit. p

In operation a signal ofone to ten-microvoltsat about 500 kilocycles maybe applied to terminals 23, .24. The primary coil it) induces anoscillating voltage in the secondary coil which is tuned by capacitor-Cto the frequency of the input signal. A.controlledself-excited amplifiedoscillation is obtained at terminals 26, 28. The output voltagerepresents a gain of as much as 200,000 to 300,000 or more. pacitor Cwere increased the self-excited oscillations would cease and no outputwould be obtained. 'The amplitude of the output can be varied byadjusting the capacitance of capacitor C An input signal as smallBattery 31 may be 2 /2 volts. Transistor 22 may-be typeSKFZZ or anequivalent.

The interceptor used is for D. C; and has a resistance of 36 o-hms'andinductance of 2.6 mh. in both-coils (500 crossings with .001 copper wirecrossed with .0008 nickel alloy #52 wire core).

Capacitor C is in series One terminal of primary quency. An inputvoltage of about one-half volt may produce an output or about threevolts in this circuit.

While I have illustrated and described the preferred embodiment of myinvention, it is to be understood that i do not limit myself to theprecise construction herein disclosed and that various changes andmodifications I may be made within the'scope of the invention as delinedin the appended claims.

if the capacitance of'ca- In Fig. 6 is shown an osciliator circuitemploying an 12. Energy feedback to sustain oscillations is applied t0the primary coil from the output of the circuit via capacitor CResistors R and R may be 4,700 ohms and 330,000 ohms respectively, Whilebattery 31 is 22 /2 volts.

In Fig. 7 is shown a discriminator circuit arranged like the circuit erPig. 5, with the exception of an input resistor R used in place ofcapacitor C This resistor is connected across terminals 23, 24. Acharacteristic frequency response curve 33 for this circuit is shown in.

Fig. 8. The circuit is designed to have peak response at 100 kilocycles.The circuit has a very sharp signal pass band of plus and minus onepercent of the'center freat two diametrally opposed points each of thecoils having coincident magnetic andgeometric axes, the axes ofthe coilsintersecting at a common central point within the coils, a first pair ofmagnetic cores encircling one intersection of said coils, and anotherpair of magnetic cores encircling the other intersection of said coils,Whereby said coils are ma netically balanced about said common centralpoint.

2. An electrical oscillation control device, comprising first andsecond'substantially flat circular-electrically conductive coils, saidcoils being interwoven and interlinked to cross each other at twodiametrally spaced points thereof, a first pair of substantiallycircular magnetic-cores interwoven and interlinked to cross each otherat two diametrallyspaced points thereof and encircling one intersectionof said coils, and a second pair of substantially circular magneticcores interwoven and interlinked to cross each other at two diarnetrallyspaced points thereof and encircling the other intersection of saidcoils, all of said cores being so disposed on the coils that all of saiddiametrally spaced points occur on a substantially com tnon diameterofsaid coils and said cores.

3. An electrical oscillation control device, comprising first and secondsubstantially flat circular conductive coils, said coils beinginterwoven and interlinked to cross each other at two diametrally spacedpoints thereof, a first pair of substantially circular magnetic coresinterwoven and encircling one intersection of said coils, and a secondpair of substantially circular magnetic cores interwoven and encirclingthe other intersection of said coils,.each ofsaid cores being agenerally toroidal winding of magnetic. wire, each of said cores havingits geometric and magnetic axis disposed at an angle of forty-fivedegrees to the geometric and magnetic axis of each of said coils, saidcoils having their geometric axes disposed atanangle of ninety degreesto each other.

4'. An electric oscillation control device, comprising a pair ofinterwoven and intersecting substantially flat circular wire coilshaving their centers positioned at the same central point, magnetic andgeometric axes of the coils being disposed at right angles andintersecting at.

said point, and means providing" a balanced magnetic field for saidcoils, said means being disposed at opposite intersecting points of saidcoils, said means comprising two pairs of intersecting and interwovenmagnetiowire cores respectively encircling. said intersecting. points.

References Cited inthe file of this patent UNITED STATES PATENTSGoodrich: lune 12, 1956

